Direct observation of the f-c hybridization in the ordered uranium films on W(110)

A key issue in metallic uranium and its related actinide compounds is the character of the f electrons, whether it is localized or itinerant. Here we grew well ordered uranium films on a W(110) substrate. The surface topography was investigated by scanning tunneling microscopy. The Fermi surface and band structure of the grown films were studied by angle-resolved photoemission spectroscopy. Large spectral weight can be observed around the Fermi level, which mainly comes from the f states. Additionally, we provided direct evidence that the f bands hybridize with the conduction bands in the uranium ordered films, which is different from previously reported mechanism of the direct f-f interaction. We propose that the above two mechanisms both exist in this system by manifesting themselves in different momentum spaces. Our results give a comprehensive study of the ordered uranium films and may throw new light on the study of the 5f-electron character and physical properties of metallic uranium and other related actinide materials.